| With the development of mobile communication technology and wireless biosensor technology,wireless medical communication technology is widely used in a variety of medical equipment.As a key part of wireless medical equipment,the implantable antenna determines the quality of wireless medical communication.The implantable antenna works in the complex electromagnetic environment of the human body,which is affected and limited by several factors.Therefore,how to design a high-performance implantable antenna has become the focus and difficulty of wireless biomedical technology research.Based on the investigation and research of current implantable medical devices,several antennas used in wireless medical communication are designed and simulated.This thesis mainly includes:1.The radiation condition of the implantable antenna in the human environment,in other words,the influence of the electrical parameters of the human tissues on the electromagnetic wave propagation is analyzed.Based on this,the factors that need to be considered in the design of the implantable antenna are summarized,such as the selection of the operating frequency band,the human body model,the limitation of volume and forms,and the human body safety limits.2.Two miniaturized circularly polarized implantable antennas are proposed.In order to alleviate the suffering of patients,the implantable antenna should be as small as possible.Therefore,the miniaturization of the implantable antenna has been a research hotspot.In addition,influenced by external factors such as human movement,a mismatch between the implantable antenna and the external receiving antenna is likely to occur.On account of these,based on different antenna design methods,two circularly polarized implantable antennas working in the 2.45GHz-ISM band are proposed.The sizes of both antennas are 8mm×8mm×1.27 mm.Compared with the circularly polarized implantable antennas proposed by the previous studies,they have a smaller volume and have stable circular polarization characteristics as well.3.An omnidirectional conformal capsule antenna is introduced.Capsule antennas work in the digestive tract of the human body,and the position and orientation are constantly changing,which is prone to mismatches with external receiving equipment,and the radiation efficiency of capsule antennas is often extremely low.For this,an omnidirectional conformal capsule antenna working in the MICS(402MHz-405MHz)band is introduced.By conforming the antenna to the inner wall of the capsule shell,it avoids the strong coupling effect between the antenna and the human body,thereby reducing the absorbing power by human body,and then by optimizing the structure of the antenna to get a larger effective aperture,and obtain a higher gain,the gain is-19.3d Bi in the end.4.A dual-band circularly polarized on-body repeater is presented.Influenced by human body,the data rate of the in-body to off-body communication system is often low and the transmission distance is short.In addition,the orientation of the implantable antenna is changed,and polarization mismatch between the implanted antenna and off-body antenna is prone to occur.Based on these,a dual-band circularly polarized on-body repeater working in the MICS(402MHz-405MHz)and ISM(2.40GHz-2.48GHz)frequency bands is proposed.The square loop slot on-body antenna proposed is fed by a microstrip line with a low profile.By adopting a C-shaped microstrip line feeding structure and loading L-shaped branches,dual-band circularly polarized radiation is achieved.The bandwidth of the antenna in the two bands(the intersection of the-10-d B impedance bandwidth and the 3-d B axial-ratio bandwidth)is 15% and 24%,respectively. |
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